In some cases, an ailment may affect the quality of a patient's sleep and/or affect the patient's activity level. For example, chronic pain may cause a patient to have difficulty falling asleep, disturb the patient's sleep, e.g., cause the patient to wake, and prevent the patient from achieving deeper sleep states, such as one or more of the nonrapid eye movement (NREM) sleep states. Chronic pain may also cause a patient to avoid particular activities, or activity in general, where such activities increase the pain experienced by the patient. Other ailments that may negatively affect patient sleep quality and patient activity level include movement disorders, and congestive heart failure. In some cases, these ailments are treated via an implantable medical device (IMD), such as an implantable stimulator or drug delivery device.
Further, in some cases, poor sleep quality may increase the symptoms experienced by a patient due to an ailment. For example, poor sleep quality has been linked to increased pain symptoms in chronic pain patients. The link between poor sleep quality and increased symptoms is not limited to ailments that negatively impact sleep quality, such as those listed above. Nonetheless, the condition of a patient with such an ailment may progressively worsen when symptoms disturb sleep quality, which in turn increases the frequency and/or intensity of symptoms. The increased symptoms may, in turn, limit patient activity during the day, and further disturb sleep quality.